1. Technical Field
The present invention relates to an image forming apparatus which comprises a toner carrier roller which carries toner on a surface thereof and an image forming method of developing an electrostatic latent image with toner using this roller.
2. Related Art
In techniques for developing an electrostatic latent image carried on an image carrier with toner, an apparatus is widely used which includes a toner carrier roller which is shaped approximately like a cylinder, carries toner on a surface thereof, and is arranged opposed facing the image carrier. For the purpose of improving the characteristics of toner carried on the surface of such a toner carrier roller, the applicant of the present application has earlier disclosed a structure of a toner carrier roller having a cylindrical shape that the surface of the roller includes convex sections which are regularly arranged and a concave section which surrounds the convex sections (JP-A-2007-121948). Since the concavo-convex patterns in the surface are regulated and uniform, such a structure is advantageous in that it permits easy control of the thickness of a toner layer which is carried on the surface of the roller, the charge level and the like.
In the image forming apparatus structured as above, toner that is not used for development at the opposed position facing the image carrier and remains on the toner carrier roller is collected in a developer, and the developer is provided with a seal member which is made of a polyethylene film or the like and abuts on the surface of the toner carrier roller in order to prevent toner inside the developer from leaking outside.